Protist Biodiversity and Biogeography in Lakes From Four Brazilian River–Floodplain Systems

The biodiversity and biogeography of protists inhabiting many ecosystems have been intensely studied using different sequencing approaches, but tropical ecosystems are relatively under‐studied. Here, we sampled planktonic waters from 32 lakes associated with four different river–floodplains systems in Brazil, and sequenced the DNA using a metabarcoding approach with general eukaryotic primers. The lakes were dominated by the largely free‐living Discoba (mostly the Euglenida), Ciliophora, and Ochrophyta. There was low community similarity between lakes even within the same river–floodplain. The protists inhabiting these floodplain systems comprise part of the large and relatively undiscovered diversity in the tropics.     

Bartonella spp. Bacteremia in Blood Donors from Campinas,Brazil

Bartonella species are blood-borne, re-emerging organisms, capable of causing prolonged infection with diverse disease manifestations, from asymptomatic bacteremia to chronic debilitating disease and death. This pathogen can survive for over a month in stored blood. However, its prevalence among blood donors is unknown, and screening of blood supplies for this pathogen is not routinely performed. We investigated Bartonella spp. prevalence in 500 blood donors from Campinas, Brazil, based on a cross-sectional design. Blood samples were inoculated into an enrichment liquid growth medium and sub-inoculated onto blood agar. Liquid culture samples and Gram-negative isolates were tested using a genus specific ITS PCR with amplicons sequenced for species identification. Bartonella henselae and Bartonella quintana antibodies were assayed by indirect immunofluorescence. B. henselae was isolated from six donors (1.2%). Sixteen donors (3.2%) were Bartonella-PCR positive after culture in liquid or on solid media, with 15 donors infected with B. henselae and one donor infected with Bartonella clarridgeiae. Antibodies against B. henselae or B. quintana were found in 16% and 32% of 500 blood donors, respectively. Serology was not associated with infection, with only three of 16 Bartonella-infected subjects seropositive for B. henselae or B. quintana. Bartonella DNA was present in the bloodstream of approximately one out of 30 donors from a major blood bank in South America. Negative serology does not rule out Bartonella spp. infection in healthy subjects. Using a combination of liquid and solid cultures, PCR, and DNA sequencing, this study documents for the first time that Bartonella spp. bacteremia occurs in asymptomatic blood donors. Our findings support further evaluation of Bartonella spp. transmission which can occur through blood transfusions.     

Evidence that dams promote biotic differentiation of zooplankton communities in two Brazilian reservoirs

Hydrobiologia - Human activities may change beta diversity—the spatial variation in species composition—in different ways. Positive and negative trends in beta diversity are referred as...     

Production of embryonic and fetal-like red blood cells from human induced pluripotent stem cells

We have previously shown that human embryonic stem cells can be differentiated into embryonic and fetal type of red blood cells that sequentially express three types of hemoglobins recapitulating early human erythropoiesis. We report here that we have produced iPS from three somatic cell types: adult skin fibroblasts as well as embryonic and fetal mesenchymal stem cells. We show that regardless of the age of the donor cells, the iPS produced are fully reprogrammed into a pluripotent state that is undistinguishable from that of hESCs by low and high-throughput expression and detailed analysis of globin expression patterns by HPLC. This suggests that reprogramming with the four original Yamanaka pluripotency factors leads to complete erasure of all functionally important epigenetic marks associated with erythroid differentiation regardless of the age or the tissue type of the donor cells, at least as detected in these assays. The ability to produce large number of erythroid cells with embryonic and fetal-like characteristics is likely to have many translational applications.     

High performance liquid chromatography analysis of a 4-anilinoquinazoline derivative (PD153035), a specific inhibitor of the epidermal growth factor receptor tyrosine kinase, in rat plasma

The quinazoline derivative, 4-N-(3'-bromo-phenyl)amino-6,7-dimethoxyquinazoline (PD153035), has recently been identified as a potential drug for the treatment of proliferative disease. Here, we report a sensitive high performance liquid chromatography (HPLC)-based quantitative detection method for measurement of PD153035 levels in rat plasma. Sample pretreatment involved a two-step extraction with chloroform. The analytes were separated on a column packed with OmniSpher C18 material and eluted with acetonitrile-0.1 M ammonium acetate, pH 7.2 (70:30, v/v). The column effluent was monitored by UV detection at 330 nm. A linear response was achieved over the concentration range 0.50-100.00 microM using multilevel calibration with an internal standard. The analytical method inter- and intra-run accuracy and precision were better than +/-15%. The lower limit of quantification was 0.50 microM. The method has been applied to study the preclinical pharmacokinetics of this compound in rats.     

Variation in ostracod (Crustacea,Ostracoda) communities in the alluvial valley of the upper Paraná River (Brazil) in relation to substrate

Large river floodplains are convenient model systems to test for variation in animal and plant community structure, as they have a variety of habitats and substrates and are generally dynamic systems through the occurrence of flood pulses with varying intensity. South American floodplain systems furthermore have unique types of substrates, in the form of root systems of floating macrophytes. Here, we investigate the variation in ostracod (small, bivalved crustaceans) communities in relation to substrates and related environmental variables. Sampling was effected in 2004 in the alluvial valley of the upper Paraná River, Brazil, in the wet and dry seasons. Five different substrates, including littoral sediment and four macrophyte species root and leaf systems, in four hydrological systems and a variety of habitat types, were sampled. Fifty-four species of Ostracoda were found. Variation partitioning analysis (RDA) showed that ostracod communities significantly differed between different substrates, mainly between the littoral and plants with small root systems (Eichhornia azurea) on the one hand, and plants with large and complex root systems on the other hand (Eichhornia crassipes and Pistia stratiotes). RDA analyses indicated that the pleuston (biotic communities associated with root systems of floating plants) of E. crassipes comprised more non-swimming species than the pleuston of the smaller roots of P. stratiotes, but species-level Kruskal–Wallis analyses could not detect significant differences between both macrophyte species. Also habitat type and hydrological systems contributed to variation amongst ostracod communities, but less so than the factor substrate. Abiotic factors also contributed to variation, but the ranges of all measured water chemistry variables were narrow. This uniformity in abiotic factors, which might be owing to the occurrence of large flooding events, unites all water bodies, even those that are generally separated.     

Size structure of testate amoebae (Arcellinida and Euglyphida) in different habitats from a lake in the upper Paraná River floodplain

This study aimed to investigate the relationship between the size structure of testate amoebae in distinct habitats, i.e. plankton, aquatic macrophytes and aquatic sediment. The samples were taken from a floodplain lake of the upper Paraná River. The assumptions we strived to scrutinize were that (i) larger mean sizes of testate amoebae would be recorded in the sediment of the lake; and (ii) temporally, smaller individuals would be registered during the high water period in all habitats. The sampling was done monthly, from April 2007 to March 2008, in triplicates for each habitat. Testate amoebae were represented by individuals sized between 20 and 400 μm. The smaller individuals predominated in plankton samples, while in the aquatic sediment the larger ones were chiefly represented. These differences were probably associated with metabolic activities, i.e. the energy needs of these unicellular organisms, in each habitat. Two-way ANOVA yielded significant differences between hydrological periods. During the high water period, the increase in rainfall and consequently in water flow, decreased the stability of the system and increased turbulence and water column circulation. Therefore, environmental stability seems to be one of the main factors driving the temporal variation in the size structure of these specific organisms.